[Kim Jaeho's Life Story] <271> Protecting Knee Cartilage Health

Diseases affecting the knee joint are not life-threatening, but they can significantly reduce quality of life due to the various inconveniences experienced in daily activities. The number of people receiving treatment for various knee joint diseases has steadily increased from 2.72 million in 2016 to 3.31 million in 2024, which is only slightly less than the 3.96 million patients treated for diabetes.

Knee joint diseases include knee osteoarthritis, which involves inflammation and pain as the cartilage in the knee joint wears away; chondromalacia patellae, where the cartilage in the knee joint weakens or becomes damaged; and patellar tendinitis, which is inflammation of the patellar tendon that connects the kneecap (patella) to the shinbone (tibia). Among these, knee osteoarthritis is the most common, so this article will mainly focus on it.

The knee joint is where the femur (thigh bone) above the knee, the tibia (shinbone) below the knee, and the patella (kneecap) in front of the knee meet. The cartilage between the femur and tibia acts as a shock absorber when tension or twisting occurs between the two bones. This flexible cartilage consists of articular cartilage and meniscal cartilage.

Articular cartilage is a smooth, hard, and highly elastic tissue that covers the ends of the femur and tibia and the back of the patella. It allows the bones to move easily within the joint and slide against each other without friction. The meniscal cartilage is a strong and flexible C-shaped cartilage located between the femur and tibia on both sides of the knee. It helps distribute body weight evenly across the knee surface and acts as a shock absorber.

As such, knee cartilage supports the body, stabilizes the joint to prevent wobbling, absorbs and disperses shocks transmitted to the knee joint, and evenly distributes synovial fluid within the joint capsule to ensure smooth joint movement. If the knee cartilage is damaged, it can cause knee pain, swelling and warmth around the knee joint, and discomfort or restriction when bending or straightening the knee, leading to a reduced quality of life.

Many people live their entire lives with healthy knee cartilage and little discomfort, but there are also many who suffer from cartilage damage. In younger patients, the cause is usually trauma, while in middle-aged and older patients, cartilage damage often occurs without any particular injury. Unlike other tissues, once knee cartilage is damaged, it does not heal easily. Therefore, it is important to understand the characteristics of knee cartilage to maintain its health.

Knee cartilage is 4 to 5 mm thick and consists of chondrocytes and extracellular matrix. Chondrocytes develop from chondroblasts, which produce the extracellular matrix. The extracellular matrix is composed of collagen fibers, matrix, and water. The matrix contains proteoglycans and glycoproteins, and water accounts for 70-80% of the cartilage's weight.

Chondrocytes have a very long lifespan and can last a lifetime if not damaged. However, unlike most other cells, they are not connected to blood vessels and receive nutrients through diffusion from surrounding tissues, which means their nutrient supply is poor. As a result, once damaged, recovery is difficult, and cell division is very limited, making self-regeneration rare. In particular, it is known that regeneration becomes extremely difficult after the age of 15.

Therefore, to maintain healthy knee cartilage, it is essential to adopt lifestyle habits that prevent cartilage damage and allow chondrocytes and cartilage tissue to function optimally. The attitude of living as one pleases and only going to the hospital when pain occurs can harm knee cartilage health and lead to a significantly lower quality of life.

As mentioned earlier, chondrocytes are not connected to blood vessels, and they are also not directly connected to lymphatic vessels or nerves. Therefore, most of the pain associated with knee osteoarthritis is caused by stimulation of the surrounding tissues.

The best approach for knee cartilage is to use it appropriately. By engaging in regular and appropriate exercise, not only the cartilage but also the surrounding muscles, tendons, and ligaments can be maintained in optimal condition. Reducing physical activity or avoiding exercise to "protect" the knee joint actually weakens the cartilage, which is a misconception. It is also important to remember that excessive exercise is not good either.

By gender, degenerative arthritis is much more common in women than in men. This is likely because women have less muscle mass supporting the bones, do more housework that puts stress on the knee cartilage, and tend to be less physically active, resulting in less exercise.

It is also important to reduce the burden on the knee joint in daily life. Maintaining a healthy diet to avoid obesity and correcting poor postures that are bad for the knee joint during work or daily activities are crucial. Special care is needed when engaging in sports or activities with a high risk of injury.

When receiving treatment for knee osteoarthritis, there are precautions to keep in mind. The basic approach is conservative treatment, which aims to restore and maintain the optimal condition of the cartilage, as well as the surrounding muscles, tendons, and ligaments, through the recovery and regeneration of their cells.

Special caution is required when receiving injection treatments. Injections are often administered for pain relief rather than healing damaged tissue. In particular, steroid injections can reduce inflammation and pain, but repeated use can cause serious side effects. Even when receiving injections for temporary relief, it is essential to combine them with appropriate exercise, including stretching and strength training.

There are also important considerations when undergoing stem cell therapy. Knee chondrocytes have limited regenerative capacity in their natural state, so many approaches using stem cells are being researched and attempted. However, their effectiveness is still limited, and even at Johns Hopkins University in the United States, which operates a cartilage regeneration clinic, this treatment method is applied only in a limited manner.

If symptoms worsen and quality of life declines despite long-term conservative treatment for knee osteoarthritis, artificial joint replacement surgery may be performed. The number of patients who underwent this surgery was about 67,000 to 69,000 per year in 2017-2018, and has remained between 71,000 and 78,000 per year since 2019. After surgery, it is very important to restore and maintain normal joint function through regular exercise and appropriate lifestyle habits.

In summary, to prevent and treat knee osteoarthritis, it is necessary to correct unhealthy lifestyle habits that damage chondrocytes and related cells and hinder the recovery of damaged cells. One should adopt lifestyle habits that allow chondrocytes and related tissues to remain healthy and function optimally. This approach is what is referred to as "Newstart" (see Life Story Part 6).

The first of the eight elements of Newstart is a "life-giving diet," which means eating a wide variety of whole, plant-based foods such as fruits, vegetables, and grains without favoring specific foods. It is also important to reduce the intake of sugar, which causes many problems when consumed in excess, as well as processed or refined unhealthy carbohydrates, saturated and trans fats, salt, and alcohol. Practicing the other elements of Newstart-exercise, water, sunlight, temperance, air, rest, trust, and love-is also essential.

Independent Researcher

This content was produced with the assistance of AI translation services.